Phases in Contrast-Enhanced CT
CT
Understanding CT Contrast Phases
The timing of image acquisition after intravenous contrast administration is crucial in CT scanning. Different phases highlight specific organs and pathologies by capturing the peak enhancement of various vascular and parenchymal structures.
Non-Contrast Phase
Timing
Before injection
Targets
Baseline tissue attenuation, calcifications, fat content, acute hemorrhage
Common Uses
Kidney stones, calcifications in tumors, adrenal adenoma HU measurement, acute hemorrhage
Arterial Phase (Early Arterial)
Timing
15–25 sec
Targets
Arteries, hypervascular lesions
Common Uses
Arterial anatomy mapping, pulmonary embolism, arterial aneurysm, hypervascular tumors (HCC, RCC, neuroendocrine)
Late Arterial / Hepatic Arterial Phase
Timing
25–35 sec
Targets
Arterial supply to organs (especially liver)
Common Uses
HCC detection, hypervascular metastases, GI bleeding localization
Corticomedullary Phase (Kidneys)
Timing
30–40 sec
Targets
Renal cortex, renal arteries
Common Uses
Renal artery stenosis, cortical lesions, preoperative renal anatomy
Portal Venous Phase
Timing
60–70 sec
Targets
Portal venous system, parenchymal organs (liver, spleen, pancreas), hypovascular lesions
Common Uses
Liver metastases detection, pancreatic tumors, bowel wall pathology
Nephrographic Phase (Kidneys)
Timing
80–100 sec
Targets
Homogenous enhancement of renal parenchyma
Common Uses
Renal mass characterization, urothelial tumors
Delayed / Equilibrium Phase
Timing
3–5 min
Targets
Fibrotic tissue, delayed contrast washout lesions
Common Uses
Cholangiocarcinoma, fibrotic tumors, adrenal washout study, urinary bladder tumors
Excretory Phase (Pyelographic)
Timing
5–15 min
Targets
Urinary collecting system
Common Uses
Urothelial carcinoma, urinary tract obstruction, post-surgical evaluation
Enteric / Late Phase
Timing
Variable (after oral contrast)
Targets
Bowel lumen and wall
Common Uses
Inflammatory bowel disease, tumors, fistula detection
| Phase | Timing | Target Structures | Common Clinical Uses |
|---|---|---|---|
| Non-Contrast Phase | Before injection | Baseline tissue attenuation, calcifications, fat content, acute hemorrhage | Kidney stones, calcifications in tumors, adrenal adenoma HU measurement, acute hemorrhage |
| Arterial Phase (Early Arterial) | 15–25 sec | Arteries, hypervascular lesions | Arterial anatomy mapping, pulmonary embolism, arterial aneurysm, hypervascular tumors (HCC, RCC, neuroendocrine) |
| Late Arterial / Hepatic Arterial Phase | 25–35 sec | Arterial supply to organs (especially liver) | HCC detection, hypervascular metastases, GI bleeding localization |
| Corticomedullary Phase (Kidneys) | 30–40 sec | Renal cortex, renal arteries | Renal artery stenosis, cortical lesions, preoperative renal anatomy |
| Portal Venous Phase | 60–70 sec | Portal venous system, parenchymal organs (liver, spleen, pancreas), hypovascular lesions | Liver metastases detection, pancreatic tumors, bowel wall pathology |
| Nephrographic Phase (Kidneys) | 80–100 sec | Homogenous enhancement of renal parenchyma | Renal mass characterization, urothelial tumors |
| Delayed / Equilibrium Phase | 3–5 min | Fibrotic tissue, delayed contrast washout lesions | Cholangiocarcinoma, fibrotic tumors, adrenal washout study, urinary bladder tumors |
| Excretory Phase (Pyelographic) | 5–15 min | Urinary collecting system | Urothelial carcinoma, urinary tract obstruction, post-surgical evaluation |
| Enteric / Late Phase | Variable (after oral contrast) | Bowel lumen and wall | Inflammatory bowel disease, tumors, fistula detection |